【作者】 万沙沙；

【导师】 裴丽；

【作者基本信息】 北京交通大学 ， 光通信与移动通信， 2008， 硕士

【摘要】 微波光子滤波器在光域内实现对微波信号的滤波,不需要复杂、昂贵的光电/电光变换,因此在ROF(Radio Over Fiber)系统中具有重要的作用。光纤光栅具有良好的波长选择性能和滤波特性,能以灵巧的方式构建具有独特性能的微波光子滤波器,所以基于光纤光栅的微波光子滤波器成为微波光子学领域内的研究热点之一。本文充分利用光纤光栅的波长选择特性,着重分析和设计了基于光纤布拉格光栅(FBG,Fiber Bragg Grating)的微波光子滤波器,主要内容和创新性工作如下:1.分析比较各种微波滤波器的优缺点,在研究了国内外各种基于FBG的微波光子滤波器结构的基础上,提出新型的高Q值可调谐微波光子滤波器结构。2.利用数值模拟方法分析FBG的结构参量对于其反射谱的影响,并利用光纤光栅作为基本的滤波元件,设计基于FBG的微波光子滤波器结构,提出几种改进结构:基于多个光纤光栅级联的共振腔谐波抑制滤波器、可调谐微波光子滤波器、平坦通带响应的微波光子滤波器。3.创新性地将DIRECT全局优化算法应用于微波光子滤波器的设计中,用C语言实现该算法来得到抽头系数,利用Matlab语言对滤波器幅度响应进行仿真,分别分析正、负、对称抽头系数对滤波性能的影响,最后进行优化设计,形状因子可达到1.3180,仿真结果表明了这种算法的可行性和有效性。4.基于保偏啁啾光纤光栅原理,利用光子来产生应用于ROF系统的微波信号,通过调谐马赫-曾德干涉仪两臂光纤长度、啁啾光栅的色散系数等参数可以实现大范围的微波频率调谐,调谐范围可从0到几百GHz。更多还原

【Abstract】 Photonic Microwave filter (PMF) can achieve filtering microwave signals in optical domain without complicated and expensive EO/OE conversion. So PMF plays an important role in ROF system.FBG has a good performance in wavelength selection and filtering. PMF with unique characters can be builded in ingenious way by employing FBG. Therefore, PMF based on FBG becomes a hot spot in the domain of Microwave Photonics.In this paper, we take full advantage of the wavelength selection of FBG to analyse and design PMF.The main work and innovative points are as follows:1. The advantages and disadvantages of microwave filters are analyzed and compared. All kinds of domestic and foreign PMF structures based on FBG are summed up. A new structure of tunable PMF with high Q is proposed.2. The impacts of the FBG parameters on spectrum are analyzed by using numerical simulation method. FBG is used as the basic filtering device to design PMF. We bring forward several advanced structures: resonance cavity harmonics suppression PMF, tunable PMF, flat-top passband response PMF.3. DIRECT global optimization algorithm is used in designing PMF the first time. We employ C language to achieve DIRECT algorithm and Matlab language to simulate the amplitude responses. The characters of PMF with positive, negative and symmetrical tap coefficient are analyzed respectively. Then the design is optimized. Shape-factor can be achieved 1.3180.The simulation results show that this method is feasible and effective.4. Based on the principle of polarization maintaining chirped fiber grating, microwave signals used in ROF system is generated. By changing the lengths of M-Z interferometer’ two arms and parameters of chirped grating, such as the dispersion coefficient, microwave frequency can be tuned from 0 to several hundred GHz.更多还原